In the past, a system for controlling a vehicle by using information obtained from a sensor such as a camera and a sonar and supporting the driver of the vehicle has been developed. A pre-crash safety system and the like that attracts attention of the driver by giving a warning and the like when the vehicle may possibly collide with an obstacle in front of the vehicle and further alleviates injury to passengers by automatic breaking when the collision is inevitable has already been put into practice as an example of such system.
In such system, it is necessary to accurately find a relative position and a relative speed of a driver's vehicle and an obstacle in order to accurately determine the collision possibility between the driver's vehicle and the obstacle, and for example, PTL 1 discloses a technique for estimating the current position of the target object on the ground surface by tracking the target object to the immediate proximity of the driver's vehicle in a case where the ground contact position where the target object is in contact with the ground surface is out of the image-capturing range or blocked.
The target object tracking apparatus disclosed in PTL 1 includes target object detection means for predicting a current position of a target object on a ground surface on the basis of a position of the target object on the ground surface and vehicle motion information derived from an image in the past and detecting the target object from a position on a current image corresponding the detected current position on the ground surface, first position estimating means for estimating the current position of the target object on the ground surface on the basis of a ground contact position on the image and an attachment position of image-capturing means to a vehicle in a case where a ground contact position where the target object is in contact with the ground surface exists within an image-capturing range, second position estimating means estimating the current position of the target object on the ground surface on the basis of the position of the target object on the ground surface derived from the image in the past and an enlargement factor of a size of the target object in the current image with respect to a size of the target object in the image in the past, and unification means unifying the current position predicted by the target object detection means, the current position estimated by the first position estimating means, and the current position estimated by the second position estimating means.
According to the target object tracking apparatus disclosed in PTL 1, in a case where the ground contact position exists in the image-capturing range, the current position of the target object is estimated on the basis of the ground contact position, and even in a case where the ground contact position does not exist in the image-capturing range, the current position of the target object is estimated on the basis of the enlargement factor of the target object on the image, and therefore, even in a case where the ground contact position where the target object is in contact with the ground surface is out of the image-capturing range or blocked, the position of the target object can be estimated by tracking the target object to the immediate proximity of the vehicle.